The invention relates to a cover, constructed as a solar generator, for closing an opening in the bodywork of a vehicle, in particular for motor vehicle sunroofs. The invention additionally relates to a method of producing such a cover.
The term xe2x80x9csunroofxe2x80x9d, used here alone or in phrases, is intended, for the purposes of the present invention, to cover not only designs in which the cover may be slid under the fixed rear roof surface to uncover the roof opening after lowering of its rear edge but also slide and lift sunroofs, in which the cover may additionally be tilted from its closed position about a tilt axis provided in the vicinity of its front edge so as to project above the fixed roof surface. Front-hinged covers which open out in the manner of ventilation shutters and sliding sunroofs in which the cover may be slid partially over the rear fixed roof surface to uncover the roof opening after lifting of its rear edge and, in some designs, also tilted (xe2x80x9cspoiler roofxe2x80x9d) are also included. Finally, the term xe2x80x9csunroofxe2x80x9d also covers multi-cover roofs, in which at least one cover may be opened out, and also roofs with removable covers or cover parts.
A cover constructed as a solar generator, hereinafter known as a solar cover, for motor vehicle sunroofs is known from DE 197 39 615 C1 belonging to the applicant. It comprises a glass panel and a solar cell field which consists of a plurality of crystalline solar cells connected together electrically and is arranged beneath the glass panel. The solar cell field is only slightly smaller in its external dimensions than the free outer surface of the glass panel, wherein a frame of a polyurethane-based plastics, which covers the external edge areas of the solar cell field from beneath, is foamed onto the solar cover with low foaming pressure. This ensures on the one hand that a solar cell field of maximum external dimensions, predetermined by the cover size, may be accommodated and on the other hand that, due to the low foaming pressure and the low temperature accompanying this pressure, the risk of breakage of and damage to the sensitive crystalline solar cells is eliminated to a considerable extent. However, the reaction rate is lower than in the case of conventional RIM (reaction injection molding) foaming processes, at which higher pressures occur. Because of the longer reaction times accompanying the low pressures, the mold closing times for the foaming molds used are longer.
In addition, to avoid damage to the solar cell assembly during production of a solar cover, it was proposed (DE 198 19 680 C1) to effect production in such a way that, first of all, a plastics frame of polyurethane is foamed onto the edge of a cover plate and then the solar cell assembly is laminated onto the inside of the cover plate. Only once this assembly of cover plate and plastics frame has been produced is a cover insert for reinforcing the solar cover adhered to said assembly at a distance from the solar cell assembly. This known method is complicated and time-consuming owing to the large number of steps to be performed in succession.
In the case of another known solar cover (DE 199 11 811 C1), the solar cells are embedded in a resilient film assembly, which extends with a marginal zone externally beyond the solar cells and is clamped sealingly between a support element and the cover panel. The clamped marginal zone serves as a seal with regard to the foamed material provided around the outer edge of the cover panel.
In the production of the known solar covers, in which a plastics frame is foamed onto the transparent panel once a solar cell field has been applied to the panel (DE 197 39 615 C1, DE 199 11 811 C1), special measures have in each case to be taken to achieve a seal, i.e. delimitation of the foaming zone with regard to the solar cell field, without at the same time damaging the solar cells.
The object of the invention is to simplify manufacture of the solar cover described above. The object also includes the provision of a method of producing said solar cover.
According to one aspect of the present invention, there is provided a cover constructed as a solar generator for closing an opening in the bodywork of a vehicle, the cover having a transparent panel with an underside on which is arranged a solar cell field, the solar cell field having outer edge areas, and the cover having a frame of plastics, which is foamed onto a peripheral edge area of the transparent panel and covers the outer edge areas of the solar cell field from below; wherein a plastics backing layer adjoining the solar cell field is foamed onto the cover over the entire surface, said backing layer covering the solar cell field completely from below and being formed in one piece with the plastics frame.
In the present construction of the solar cover, the solar cover is foam-backed over its entire underside, such that the solar cell field is arranged without mutual vertical spacing between the transparent panel and the foamed backing layer. Since the frame is formed in one piece with the backing layer, no seals have to be provided between the frame and the solar cell field, because the frame and the backing layer adjoining the solar cell field form a unified foaming zone. Because in particular of the lack of seal contact pressure against the solar cell field, damage to the crystalline solar cells is ruled out. The foaming process may be performed at comparatively elevated foaming pressures of  greater than 1 bar, whereby the reaction rate increases and the mold closing time is reduced. The backing layer may be foamed directly onto the solar cell field, i.e. the crystalline solar cells embedded in resilient plastics material, without the interposition of an additional backing or protective film, which further simplifies production.
Due to the closed, foamed-on backing layer on the underside of the cover, there is an advantageous freedom of design with regard to the cover underside. For instance, it is not only possible to foam rigid profiled bars into the frame at a distance from the solar cell field to reinforce the frame. It is also possible to provide ribbing or other shaping, for example in the form of a transverse rib extending through from one frame side to the other, into which a reinforcing profile may be foamed. It is also possible to form receiving spaces for electrical/electronic components on the backing layer.
To accommodate a direct current converter and for direct contacting thereof with the power line of the solar generator, a receiving space may be formed laterally on the frame, such that very short connecting lines are possible, whereby low line resistances and high efficiency are achieved.
According to another aspect of the present invention, there is provided a method of producing a cover constructed as a solar generator for closing an opening in the bodywork of a vehicle, the cover having a transparent panel with an underside on which is arranged a solar cell field, the solar cell field having outer edge areas, and the cover having a frame of plastics, which is foamed onto a peripheral edge area of the transparent panel and covers the outer edge areas of the solar cell field from below; wherein a plastics backing layer adjoining the solar cell field is foamed onto the cover over the entire surface, said backing layer covering the solar cell field completely from below and being formed in one piece with the plastics frame; the method comprising the following steps:
a) a solar cell field, embedded in a resilient film assembly, is attached to the underside of the transparent panel so as to extend into the outer edge areas thereof;
b) the transparent panel with solar cell field attached thereto is inserted into a bottom part of a foaming mould in positioned manner, said bottom part comprising a peripheral depression shaped in accordance with the frame structure and a substantially shallow recess connected on all sides with the shaped depression and spaced approximately evenly from the underside of the solar cell field;
c) after closure of the foaming mould by a mould top, the shaped depression, the shallow recess and the backing layer on the backing layer are jointly back-filled with foam at a pressure of  greater than 1 bar; and
d) the mould top is removed and the finished solar cover with frame and backing layer moulded in one piece thereon is removed from the mould bottom.
If strengthening or reinforcement is provided for the solar cover and/or the contacts connecting in current-conducting manner with the solar cells of the solar cell field are to have an easily couplable and uncouplable outlet in the manner of a socket/plug, rigid profiled bars and optionally reinforcing profiles and optionally plug connection elements or the like are inserted into the bottom of the mold in positioned manner prior to implementation of method step b), such that they are embedded in the foamed plastics during the foaming process without touching the solar cell field or, in the case of the plug connection elements or the like, are molded on or in indirectly or directly during the foaming process.